In general, water-cooled combination electrodes comprise a heat exchanger and a graphite electrode affixed to said heat exchanger by means of a threaded nipple, with the heat exchanger and the graphite electrode each being cylindrically shaped and aligned in nippled condition. The heat exchanger is connected to a cooling water system by means of cooling water guides and has to be disconnected from the same when the electrodes are replaced. During the replacement of electrodes, which is necessary when new, unconsumed graphite electrodes are mounted by means of threaded nipples, the combination electrode is disconnected from the water circuit until it can again be connected to another water circuit in the nippling jig. The period available for this process is relatively short, as the water inside the heat exchanger is growing warm.
It is desirable therefore, to keep the period between the disconnection of the cooling water supply from the electrode on the electric arc furnace in the operating position, and its reconnection, with the electrode in the nippling jig, as short as possible. As the period during which the electrode is transported from the electric arc furnace to the nippling jig is determined by the manipulation time of the crane, it is only the disconnecting and reconnecting of the cooling water ducts that can be optimized. One possibility to shorten the period required for these operations is to automate the disconnection and reconnection of the water ducts.
As the manual connection and disconnection operations have to be carried out above the electric arc furnace, an automation of this process is desirable also from the viewpoint of industrial safety.